Radiation-imaging inspection system is a necessary facility for the custom, the airport for civil aviation, and railway system. The radiation-imaging inspection system includes a fixed radiation source and an array detector which can receive radioactive rays passing through the vehicle to be inspected, the fixed radiation source and the array-detector are arranged in an inspection passage capable of shielding radioactive rays. The inspection system needs a special trailing unit so as to move a vehicle carrying containers to be inspected through the radioactive rays. The radioactive rays passed through the containers are transmitted to the array detector, the array detector then reflects the density distribution of the objects loaded in the containers based on variations of intensity of the radioactive rays, thus obtaining a perspective view of the objects loaded in the containers by converting intensity of the radioactive rays into gradation of image.
In the prior art, the above special trailing unit mainly employs a flat bed trailer or a plate-chain conveyer, for example, the No. 2000 type containerized cargo/vehicle inspection system manufactured by Rapiscan Company (US) employs a flat bed trailer, in which the truck carrying containers is driven onto the flat bed trailer and the flat bed trailer carrying the truck is then passed through the radioactive rays. The flat bed trailer occupies a large area of land and is high in manufacture cost. In addition, the flat bed trailer can not stably run and locate fixedly and reliably the vehicle to be inspected thereon, thus causing the image poor quality. Further, it is not convenient for the vehicle to be driven onto the flat bed trailer because the flat bed trailer is high relative to the ground. With the plate-chain conveyer, polygon-effect occurring therein shall cause deteriorated image and high noise.
In order to solve the above problems in the prior art, the present applicant filed a patent application CN1500685A, entitled “a trailer of an automatically scanning-type radiation inspection system for large-sized object”, on Nov. 15, 2002 to the Chinese Intellectual Property Office, the trailer has low noise, occupies less land and is low in manufacture cost. In addition, the stability of the trailer is increased, the height of the trailer body is decreased, therefore, it is convenient for the vehicle to be driven onto the trailer. Moreover, there are additionally provided with means for locating the wheels of the vehicle and for anchoring the trailer. However, the main frame of the above trailer is manufactured by fixing steel plates integrally, and a plurality pairs of guide wheels are mounted under the integral main frame, in order to avoid the torque generated during running of the guide wheels on the rails, the rails should be arranged accurately, in addition, the slope daises are fixedly connected to the trailer body, so that it is inconvenient for the trailer to be mounted and used, and adaptability of the system is poor. Further, anchoring of the trailer is achieved by engagement of anchoring hooks provided on the trailer with wedges fixed on the ground, so that reliability, stability and practicability are poor.